The present invention relates to an upper vehicle-body structure of a vehicle comprising an inflator which is provided on the inside, in a vehicle width direction, of a pair of roof side rails and capable of supplying a gas pressure to an airbag, and in particular, to an upper vehicle-body structure of a vehicle which further comprises a roof reinforcing member arranged in back of a pair of pillars with an offset distance.
Conventionally, in a vehicle equipped with a curtain airbag, the curtain airbag is stored along an inside face, in a vehicle with direction, of a roof side rail in its folded state, and covered with a roof trim at its vehicle-compartment side. Thereby, at a vehicle's side collision or rollover, a gas pressure from an inflator is supplied to the curtain airbag, thereby expanding the curtain airbag and opening a lower end of the roof trim, so that the curtain airbag projects toward the vehicle compartment along a side-window glass and inflates beside a passenger.
Japanese Patent Laid-Open publication No. 2009-262662 discloses a roof structure of a vehicle, which comprises a center frame (roof reinforcement) extending between a pair of right-and-left roof side rails and a load-transmitting member (gusset) connected to the roof side rails and the center frame and capable of adjusting a bending stress occurring at the center frame at a vehicle side collision. Herein, a curtain airbag in a stored state is arranged below the center frame and between an inside face, in the vehicle width direction, of the roof side frame and an outside end, in the vehicle width direction, of the center frame.
In general, the curtain airbag in the stored state may be configured to be used in common as a front airbag for a passenger seated in a front seat and a rear airbag for a passenger seated in a rear seat, so that the curtain airbag is provided to extend longitudinally over a center pillar positioned between the front seat and the rear seat. Accordingly, the inflator is arranged at around a position right above the center pillar which is located at a longitudinally-central position of the curtain airbag in order to stabilize an inflation performance of the curtain airbag for the front-seat passenger and the rear-seat passenger by equally supplying the gas pressure to the airbag for front seat as well as the airbag for rear seat.
Japanese Patent Laid-Open publication No. 2009-78695 discloses an upper vehicle-body structure of a vehicle, which comprises a pair of right-and-left center pillars, a pair of right-and-left roof side rails extending in a vehicle longitudinal direction, a roof reinforcing member extending in a vehicle width direction over the pair of center pillars, a curtain airbag arranged on the inside, in the vehicle width direction, of each of the roof side rails, and an inflator capable of supplying a gas pressure to the curtain airbag. Herein, the inflator is arranged in back of the roof reinforcement and at an inside face, in the vehicle width direction, of the roof side rail.
Herein, there is a desire of lowering the vehicle's height to improve the aerodynamic resistance of a vehicle or from a designing perspective, or there is a desire of enlarging an ingress-and-egress opening to improve easy ingress and egress of passengers. Accordingly, it may be preferable that the vertical width of the roof side rail be made smaller. However, since the inflator is arranged below the center frame, i.e., in a storage recess portion which is formed at the roof side rail in the above-described first patent document, it is necessary that the roof side rail ensures an arrangement space by arranging the inflator and the center frame in a vertical direction, so that it may not be easy to make the vertical width of the roof side rail properly small, keeping an appropriate installation of the curtain airbag to a vehicle body.
Since the inflator is arranged at an offset position rearward from the roof reinforcement in the upper vehicle-body structure of a vehicle disclosed in the above-described second patent document, the roof reinforcement and the inflator can be positioned at the same level, so that the vertical width of the roof side rail can be made smaller. However, in a case in which the arrangement position of the inflator is offset longitudinally from the longitudinally-central position of the curtain airbag configured to be used in common as a front-seat airbag and a rear-seat airbag, there occurs a difference in the gas-supply time between the supply to the front-seat airbag and the supply to the rear-seat airbag. Accordingly, the expansion characteristics of the front-seat airbag becomes different from those of the rear-seat airbag, so that there is a concern that the stable inflation of the curtain airbag for both a passenger seated in the front seat and a passenger seated in the rear seat may not be ensured.
Further, there has been recently a tendency of diversity of vehicle design, such as a large-sized opening portion of a sunroof or the like, or an increase of a windshield's slant angle. In order to achieve this diversity of vehicle design, it may be required to arrange the roof reinforcement interconnected the right and left center pillars in back of the center pillars. Accordingly, the inflator is offset further rearward from the longitudinally-central position of the curtain airbag, so that there is a concern that the offset amount of the possible arrangement position of the inflator from the best arrangement position (around the position right above the center pillar) of the inflator for its stable inflation may be improperly large.